Thermomechanical processes in firing clays of polymineral composition

Thermal expansion and shrinkage in firing polymineralic clays was studied by dilatometry using model specimens, and the effect of the main parameters, viz., density and size of the specimens, and heating rate, on these processes was investigated. It was shown that the thermomechanical curve of the specimen during firing largely depends on the physicochemical transformations occurring in the material, changing almost linearly in the established heating range. The density and size of the specimens and the heating rate affect the properties of green bodies but not those of fired bodies. The results make it possible to estimate transformation kinetics and can be used to substantiate optimum firing regimes for ceramic parts based on polymineralic clays. 7 refs.